Questions before self-leveling compound for hydronic floor heating on concrete slab.

[Björn_Nilsson]

Hello.
I am planning to install foam board, underfloor heating pipes in staples with barbs, reinforcement, and finally self-leveling compound. The height to the finished floor is about 110 mm from the concrete. Basement below. Some questions:
1. Will 50 mm foam board be too tight if everything has to be covered with compound?
2. Is a reinforcement mesh really needed considering it's a concrete slab?
3. Skip the staples and lay the reinforcement mesh directly on the foam board and tie the pipes to the mesh?
4. How to attach the foam board to the concrete? Glue? Foam adhesive? Screw/washers?
5. How do you seal between the boards?
6. How do you seal against the adjacent parquet floor when it's currently open underneath?

I'm terrified that the compound will leak when the pump truck leaves and there will be dips or islands of foam board in the compound...

If you don't have answers to everything, maybe you have answers to something. 😬

 

[roberob]

Hello.
I will lay down foam board, underfloor heating pipes in herringbone strips, reinforcement, and finally self-leveling compound. The height to the finished floor is approximately 110 mm from the concrete. Basement below. A few questions:
1. Will it be tight with 50 mm foam board if everything is to be covered with the compound?
2. Is a reinforcement mesh actually needed considering it's a concrete slab?
3. Skip the strips and lay the reinforcement mesh directly on the foam board and tie the pipes to the mesh?
4. How to attach the foam board to the concrete? Glue? Foam sealant? Screw/washers?
5. What do you seal between the boards with?
6. How do you seal against adjoining parquet flooring, as it is now open underneath?

I'm terrified that the compound will seep away when the pump truck has left and there will be depressions or islands of foam board in the compound...

If you don't have answers to everything, maybe you have answers to something. 😬

Point 3. That's how they did it for me. I outsourced the job. They laid 70mm foam board on the concrete slab, then some kind of fabric that was folded up against the walls to "hold" the self-leveling compound. It was sealed with foam sealant in gaps, silver tape etc.
I think the total was approximately like yours, maybe slightly more (120-130mm).

Didn't need to seal between the foam boards.
However, they had to apply a layer of self-leveling compound to even out the uneven slab.

You can place a foam board "on edge" against the parquet floor so that it doesn't run against it.

 

[Björn_Nilsson]

Point 3. That's what they did at my place. They subcontracted the job. They laid 70mm of cellular plastic on the concrete slab, then some kind of fabric that was folded up against the walls to "hold" the self-leveling compound. It was sealed with foam in cavities, duct tape, etc.
I think the total was about the same as yours, maybe a bit more (120-130mm).

No need to seal between the cellular plastic sheets.
However, they had to apply a layer of self-leveling compound to even out the uneven slab.

You can place a cellular plastic sheet on its "edge" against the parquet floor so that it doesn't run against it.


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Interesting and thanks for the reply. Did they tape the seams in the fabric?